Why can't I see and select 'Loan Out' when editing an Offer?
You only see 'Loan Out' on the Custom tab (depending on your Offer handling settings) IF the Crew member has already specified (in their existing account) that they have a Loan Out company on the 'Company' tab in their Startpack.
This way, the Project doesn't need to know if the Crew member has a company or not (Crew do that bit). The Project are just saying, 'Yes, based on this job title and our understanding of HMRC and Appendix 1, we permit this role/offer to be Self-Employed (& therefore could be Loan Out if crew member has a Loan Out company)'.
Why isn't the allowance capping at the right time?
Let's say you're paying a Crew member a weekly 'Box rental' allowance (for use of their tools of trade).
When using Timecards in Engine (using Timecard Standard or Premium only), the allowance payments will cap (stop being paid) when the cap (if specified in their Offer, e.g. at 50% of the insurance-replacement value of the tools) is reached.
However, your project started paying this Crew member their allowance prior to Timecards being used in Engine; obviously Engine doesn't know how much you've paid, but someone with Accounts Admin or Accounts Controller admin rights is able to edit the 'Paid so far' value for said Crew member:
Click Timecards > Approve tab
Click on Crew member name (to go to 'Crew View')
Scroll to beneath the days
Click 'Paid so far'
Edit the value accordingly (i.e. to the amount already paid in reality by the end of the previous working week)
The amount paid so far in timecards for subsequent weeks will now show correctly, and also cap on the week you expect.